maria-discuss team mailing list archive

[AskMonty KB <noreply@xxxxxxxxxxxx>]

Hello,

A new question has been asked in "Aria" by trsystran:
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Using MariaDB 5.5.31 (deb file for ubuntu 12.04 amd_64: 5.5.31+maria-1~precise).

When a query requires an internal temporary tables, and this tables becomes too large to be kept in ram, the table is moved to disk using Aria engine.
If the on-disk .MAD file reaches 4GB, an error occurs:
{{{
[ERROR] mysqld: The table '/tmp/#sql_74e_0' is full
}}}

How can we change this limit?


In https://kb.askmonty.org/en/aria-max-table-size/ it is recommended to change MAX_ROW, but it only applies for explicitly created temporary tables.


Looking at the code I found this in maria_create():
{{{
data_file_length= ((((ulonglong) 1 << ((BLOCK_RECORD_POINTER_SIZE-1) *
                                               8))/2 -1) * maria_block_size);
}}}

Which amounts to 4GB with default values (8192 for maria_block_size).
I created a new DB with aria-block-size = 32768 (the max value), and it still failed at 4GB.
Even if it worked, it would mean the max size is only 16GB, and setting a large block size may have performance penalties.


So what is the proper fix to increase this limit?


With MyISAM as on-disk temporary tables engine the limit seems to be much higher (at least 14GB from experiments).

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To view or answer this question please visit: http://kb.askmonty.org/en/aria-max-table-size-for-internal-on-disk-temporary-tables/